The impact of light intensity on metabolomic profile of Arabidopsis thaliana wild type and reticulata mutant by NMR spectroscopy

Light acclimation involves biochemical, metabolic and developmental adjustments that allow plants to cope with a vast range of growth environments. Arabidopsis thaliana mutants with photoperiod-dependent defects in leaf development and metabolism have been instrumental in deciphering the interlinked regulatory networks in plants. The reticulata (re) mutant displays dark green veins and pale green mesophyll tissues when grown under long day conditions. RE is a chloroplast envelope membrane protein of unknown function and is required for accurate primary metabolism and leaf development under long photoperiod, while its functional significance under short photoperiods has remained poorly understood. In the present study we assessed whether RE impacts primary metabolism or leaf development when Arabidopsis plants acclimate to different light intensities under short photoperiod. We show that growth under short day conditions annuls the metabolic and developmental defects of re mutants, suggesting that RE does not significantly modulate leaf development or primary metabolism under short photoperiod. Based on proton nuclear magnetic resonance spectroscopy (H-1 NMR) and statistical analysis, however, the metabolite profiles of differentially light-acclimated short-day-grown plants differ with respect to sugars (glucose, fructose and sucrose), TCA cycle intermediates (fumaric, malic, citric and succinic acids) and fatty acids, which become more abundant under high light. Moreover, in contrast to isoleucine, leucine, valine, threonine, serine, tyrosine and phenylalanine, which show increased abundance in highlight-acclimated plants, the contents of alanine, glutamine, glutamic acid and aspartic acid are higher when plants grow under normal growth light. These findings indicate that NMR can detect high-light-induced metabolic adjustments that arise upon plant acclimation to light stress.